pbo-readpixels-small: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/lib64/piglit/bin/pbo-readpixels-small - from package: piglit

You may install the required package with command yum install {package}

Error in other languages:
pbo-readpixels-small: bevel nie gevind nie
pbo-readpixels-small: comandă negăsită
pbo-readpixels-small: comando não encontrado
pbo-readpixels-small: commande introuvable
pbo-readpixels-small: command not found
pbo-readpixels-small: käsku ei ole
pbo-readpixels-small: không tìm thấy lệnh
pbo-readpixels-small: komanda nerasta
pbo-readpixels-small: Kommando nicht gefunden.
pbo-readpixels-small: kommandot finns inte
pbo-readpixels-small: komut yok
pbo-readpixels-small: nie znaleziono polecenia
pbo-readpixels-small: níor aimsíodh an t-ordú
pbo-readpixels-small: no se encontró la orden
pbo-readpixels-small: no s'ha trobat l'ordre
pbo-readpixels-small: opdracht niet gevonden
pbo-readpixels-small: parancs nem található
pbo-readpixels-small: perintah tidak ditemukan
pbo-readpixels-small: príkaz nenájdený
pbo-readpixels-small: příkaz nenalezen
pbo-readpixels-small: команда не найдена
pbo-readpixels-small: командата не е открита
pbo-readpixels-small: 命令找不到
pbo-readpixels-small: コマンドが見つかりません